When Princess Diana and Prince Charles announced the news of their divorce in 1996, the world was stunned — but no two were more shocked than Queen Elizabeth and Prince Philip. Obviously they, along with the rest of us, knew there were all kinds of problems but what marriage doesn’t have its trials and tribulations? If the Queen’s marriage could survive every bump along the way, so too, should Diana and Charles’, right?

Nope. Because it was just too much, what with the details of Charles’ longtime affair with Camilla Parker Bowles coming out and Diana’s eventual confrontation with her husband’s mistress; Di and Chuck were going to see their 1992 separation through. Being unhappy for the sake of staying together was never going to happen.

The real catalyst behind the decision to actually divorce was Diana’s mind-blowing interview with Martin Bashir. Once the princess revealed–so very publicly–that there were “three people” in her marriage, the Queen figured enough was enough and stepped in to advise both Diana and Charles to end it officially.

Philip, however, wasn’t as impartial as Elizabeth and the Duke of Edinburgh clearly supported his daughter-in-law over his son.

“Charles was silly to risk everything with Camilla for a man in his position,” he wrote. “We never dreamed he might feel like leaving you for her. I cannot imagine anyone in their right mind leaving you for Camilla. Such a prospect never even entered our heads.”

Philip and Diana exchanged notes, with Di referring to him as “Pa,” and both ending letters with affectionate “with fondest love” sign-offs. It’s clear that they shared a bond and truly adored each other, but even though Philip did express his sympathy and took her side, he suggested that Charles wasn’t entirely to blame and that Diana had a role in their marriage’s demise as well.

Philip asked Diana to look “honestly” into her heart and ask whether “Charles’s relationship with Camilla had nothing to do with your behaviour towards him in your marriage.” He also made it clear that he and Elizabeth would not be down with either Diana or Charles “having lovers.” So much for the time-honoured position of royal mistress, divorce was the only way to go.

Time heals all wounds, though. Charles and Camilla have been married since 2005 (and together long before, har, har) — almost as long as he and Diana. And Philip and Elizabeth have accepted it. Frankly, they really had no choice. And now they’re one big happy family.